Effect of sulphur and phosphorus levels on the accumulation of protein in Dunaliella salina


Bosscher Navarro, Laurens 


Rapid population growth, accompanied with increasing life expectancy of the population, and major environmental concerns demand the search for new novel sources of food. For this reason, microalgae are taking higher relevance in the food industry, as an alternative for conventional food, owing to their capability of being Single Cell proteins, with the capability of producing great quality protein.
The species Dunaliella salina has been used in the industry for the obtention of carotenoids, as it is one of the biggest natural resources for this added value components. But Dunaliella salina also has shown to be a plausible source of protein, with great characteristic that could be exploited in industrial production.
This study sought to assess how the growth and the protein production, is affected by different concentration of macronutrients (phosphorous and sulphur) in the medium of culture. The different concentrations used for the phosphorous are: 0.14, 0.07, 0.035, 0.0175 and 0.00875 g/L of KH2PO4, and in the case of the sulphur the concentrations are: 2, 1, 0.5, 0.25, 0.125 and 0.0625 g/L of MgSO4*7H2O.
It was observed in both conditions, that as more concentration of the macronutrients was supplied more protein and growth was obtained. Dunaliella salina showed an increase in protein production by 1,04-fold and 2,08-fold in the sulphur and phosphorous experiment, respectively, in comparison to using standard conditions of the Modified Johnson medium1 ( 0.5 g/L MgSO4*7H2O and 0.035 g/L KH2PO4). Other possible advantages for the industry also were observed.
The protein concentration in samples with less biomass growth was higher in the sulphur experiment, obtaining 75-79% of the biomass/protein ratio (in sample sets with, 0.125 and 0.0625 g/L of MgSO4*7H2O).
In the phosphorous experiment differences in the time of growth provoked that the concentration of protein varied greatly between sample sets. Observing that a major availability of exogenous phosphorous in a concentration of 2 g/L of MgSO4*7H2O, may give higher growing time under low light irradiation conditions. As biomass and protein production were the highest of the experiment over this sample set. As well as being able to grow until the 26th day, in comparison to other sample sets that had grown until the 16th day, thus observing the survival advantage.
Other analytes were also studied, but the results turned inconclusive in the glycerol analysis, and a side test was done to observe differences between fresh samples and frozen ones at -20ºC. Concluding that if the samples are to be analysed for its glycerol content, the samples must be fresh. Because in the storage conditions glycerol is degraded, enhancing the need for more studies to be made, in order to obtain conclusive results.



Garcia Triñanes, Pablo
Leivar Rico, Pau; Sui, Yixing


IQS SE - Undergraduate Program in Biotechnology